Apparatus for evaporating liquid



Nov. 10, 1931. EHRHART 1,831,233

APPARATUS FOR EVAPORATING LIQUID Filed June 3, 1926 IVENTOR presentinvention deals.

Patented Nov. 10, 1931 unireo s'rA'rEs PATENrorrlcef,

RAYMOND N.-EHRHART, or PITTSBURGH, PENNSYLVANIA, AssreNon TO ELLIOTTeoivr PAINY, or PITTSBURGH, PENNsYLVANI A CORPORATION or PENNSYLVANIAAPPARATUS FOR EVAPORATING LIQUID 7 Application filed June 3, 1926.Serial No. 113,427;

The present invention relates broadly to the art of heat exchanging andliquid treat ment, and more particularly to an improved high pressuresteam for .the development of energy in mechanical or other forms, thesteam in passing throughlthe particular apparatus used giving up acertain portion of its thermal energy. This portion of thermal energy sogiven up is in turn transformed by the'apparatus into another form ofenergy such as mechanical energy. The greater portion of the thermalenergy of the steam, however, is not utilized by the apparatus, so thatthe steam rejected thereby carries away with it by far the greaterportion of its original thermal energy. In other words, the thermalenerg in the exhaust of standard apparatus, such for example, a steamengine, is many times that which has been utilized by the engine. -hethermal energy content of exhaust steam under such conditions is usuallyreferred to as degraded or lower level heat.

In the operation of apparatus utilizing steam, it is necessary in orderto obtain the maximum range for the utilization of heat to have theapparatus exhaust into. a region having the lowest possible, or at leastthe lowest practical pressure, which in connection with steam" means thelowest temperature. For practical purposes such a condition of lowpressure is conveniently produced by means of condenser, thetemperatures maintained by a condenser usually being jso'low thatthereis no way of utilizing all of the low level heat in the range asmaintained by the condenser. It is, however, possible to reclaim smallportlons the low level'heat that would ordinarily be rejected to thecondenser, and it is with this phase of the operation that the Oneobject oft-he presentinvention, therefore, is to effect a saving andpractical utilization of a portion wh ch is ordinarily of the degradedheat thrown away. f

In the accompanying figure of the draw ing, which figure is largelydiagrammatic and A representative of one embodiment of the mventicn,have shown for purposes of illustration only one system by means ofwhich theinvention may be carried out and a portion; of the low levelheat effectively utilized.

In carrying out the present invention there may be provided a condenserQof the twosurface type and of any desired construction and hereinafterreferred to as the main condenser. V lVater may be circulatedv throughthe tubes of the condenser by a suitable pump 3 and discharged therefromthrough an outlet 4, while steam may be delivered to the 7 space aroundthe tubes through the inlet 5,

such steam obviously being led from the engine or other apparatus whichthe condenser serves. Usually, all of the heat in the exhaust steamdelivered through the inlet 5 is communicated to the cooling. watersupplied. to

the condenser, which cooling water in turn,

goes to waste. In accordance with the present lnvcntlon, a portion ofthe heat which is 'thus normally wasted is diverted and utilized in aprocess of liquid evaporation effective for evaporatingv a suiliclentquantity of raw water for example, to make up the losses in distilledwater incldent to normal power plant operatlOIL' i I Y In accordancewith this featureof the in with an offtake conduit 6 through which aport onof the'exhaust steam led to the main condenser may be conductedto a second convvention I may provide the main condenser denser 7 this.condenser being hereinafter referred to as a heater condenser. Theheater condenser is materially smaller in size than the main condenserbut may otherwise be of a construction generally similar thereto.

Cooling water for the heater condenser may be delivered through aconduit Sand-dis. charged through a connection 9 hereinafter more fullyreferred to. COOperatingWith the heater condenser is an alrexhaustmg.means 10 herein illustrated as discharging through the conduit 11directly into the main condenser. As the pressure in the mainlcondenseris not" materially different from that in the heater condenser, it willbe apparent capacity may be realized. By the use of a relatively largeexhausting means the ciliciency of the heater condenser may be madecomparatively much greater than is possible for practical operatingreasons with the main condenser. For purposesot illustration only, andnot for limiting the, present invention, it may be pointed out that amain condenser requires such differences in heat head between thewaterand steam spaces that the discharge water is usually at least andgenerally lower in temperature than the temperature of the steam beingcondensed. Also, condensers with ejecting or exhausting, means of thegeneral character'illustrated by the exhausting means 10 for the heatercondenser requirea much less heat head. For example, a2,,000 squarefootcondenser receiving steam from the inlet of the main condenser willextract 18,000-poundsof steam per hour, and the, irculating waterleaving; such condenser will be heated to. within. a fraction of adegree oi the temperature of the. heating steam. also, findillZLlJSllCll results are. accomplished with. a. steam. ejectorv having,a steam consumption of but. pounds an hour, such an operatlOIl beingobtainable 111th an exhausting i 1 5g? 9 2 6811 6156 30;tmliglig gggg Hotcw- A. H I gm 2110p Leann"? arr srkm i greater in all cases than thevacuum maintamed in the main condenser. I have found that it is possibleto so proportion the high vacuum condenser with respect to surface area,amount that. it 1s prac tically possible to maintain a vacuum therein,

steam temperature lower than that in f circulating area, and the like,

the incident of which is from 10 to 15 the main condenser.

The high vacuum condenser 14 has its vapor space" operatively connectedthrough a suitable conduit 15 with the vapor ofltake l6 from a flashchamber 17.

By reason of this relationship, there is maintained in the vapor flashchamber the same high vacuum which exists 1n the vapor space. of thespace of the high vacuum condenser. water from the The circulatingheater condenser passes through the outlet 9 directly to the flashchamber. In view of the fact that the heater condenser .maintains a the,circulating water I while the: condenser 14s maintains a high vachightemperature in discharged thereby,

uum, the water passing through the connection 9 to the flash chamberwill be at a temperature higher flash. chamber, whereby a than thetemperature of the certain poruon this 11111111 01.

11W) 21119111 11119gsuput 01.

181 1 1 a e??? MPGIGP) 6913,0911] 1101 I P101! 5) c0 Pi Wang; iHLG ergo4m", i W Hag] F P 11 D6 am a FP vITT- continuously passing by means ofsuitableconnections 24 through the interand after condensers.

From the foregoing description it will be ap-.

parent that I amenabled by means of low level temperature steam to heatwaterto be evaporated to substantially the maximum temperature possible,and thereafter, flash a part ofthis water in a chamber havinga vacuummaintained therein of such a degree that the heated water will flash.Thereafter, the flashed water is condensed, recovered, and delivered tothe desired point as distilled water.

I am aware that it has heretofore been proposed, as illustrated forexample in the patent to Forbes, No. 1,232,269 of July 3, 1917, to takewater from the discharge of a'main surface condenser and flash it toobtain distilled water. Installations of this character, however, havenot been feasible or practical from a commercial standpoint for thereason that with such condensers there is very little rise in thetemperature of the circulating water, and therefore, no opportunity forobtaining a sufficient heat head to insure sat-v isfactory operation.Furthermore, any fall'- ing oil in theefficiency of the condenser willresult in even poorer operation. In all cases of such nature it isproposed to flash the water in a flash chamber, the vacuum of whichcorresponds to the vacuum of the main condenser from which the water isextracted. In accordance with the present invention I not only overcomedifiiculties of the nature vacuum condenser capable of giving veryefficient performance. It is so proportioned as to have the ability towithdraw gases and vapors from the high vacuum condenser with a vacuumexisting therein of greater magnitude than is ordinarily encountered incondenser installations. As an example of this condition, it will befound that main condensers with water temperatures incident to thewinter season will maintain vacua the temperatures of which are 70 orevenlower. In such cases, if'I wish to obtain flash gradiouts of 15,there must be provided an ejeotor capable of handling fluidfrom the highvacuum condenser, the pressure of which fluid in inches of mercury isless than .4 of

' an inch absolute. hile'the invention is distively with a maincondenser of the jet type;

I furtherrealize that whilethe present embodiment of theinventionillustrates utilizing heating steam from the main condenser Also, whileI have herein referred to a :2

flash temperature gradient of 10 or 15, and while, for practicalpurposes it is desirable to have a flash temperature gradient as high aspossible, I find that a 5 gradient Will give fairly satisfactoryoperation. It is desirable, however, under the majority of conditions tomaintain a temperature gradient for flashing purposes in excess of 5.

Certain advantages of the present invention arise from the provision .ofan apparatus by means of which it is possible to vreclaim small portionsof the lowlevel heat that are ordinarily rejected to the main condenser.

Other advantages of the present invention arise from the provision of anapparatus operatingto recover the thermal energy of degraded or lowlevel heat and utilizing such energy for the production ofdistilledwater.

Still further advantages of the present invention arise from the methodof treating liquids in such manner that the thermal energy ofdegraded orlow level heat may-be effectively utilized for. producing temperaturessufficiently high that evaporation of certain quantities of liquidmay beobtained and the energy of such steam thereby recovered. r

I claim: 5 v

1. 'In a heat exchange apparatus, a main condenser, a heater condenser,means for supplying low level; vapor to said condensers, a gas olftakefrom the heater condenser to the main condenser, meansfor maintaining alowerpressure in the heater condenser than in the main condensers, aflash chamberreceiving water from said heater condenser, and meansmaintaining a .lower pressure in said flash chamber than the pressure insaid main condenser.

In a heat exchange apparatus, a mainv condenser, a heater condenser,means for.

supplying low-level vapor to said condensers, a olftake from the heatercondenser to the main condenser, means for maintaining a lowerpressure'in the heater condenser than in the main condensers, a flash chamberreceiving water from said heater condenser, V and means maintain ng alower pressure in said flash chamber than" the pressure in the vaporinlet of said main condenser, said last mentioned means comprising ahigh vacuum condenser.

3. In a heat exchange apparatus, a'main condenser, a heater condenser,means for supplying low level vapor to said condensers, a gas cfltakefrom the heater condenser to the main condenser, said offtake includingexhausting means, a flash chamber receiving water from said heatercondenser, and means maintaining a lower pressure in said flash chamberthan the pressure in vapor inlet of said main condenser.

4. In a heat exchange apparatus, a main condenser, a heater condenser,means for supplying low level vapor to said condensers, a gas ofltakefrom'the heater'condenser to the main condenser, said ofttake' includingexhausting means, a flash chamber receiving Water from said heatercondenser, and means maintaining a lower pressure in said flash chamberthan the pressure in vapor inlet of said main condenser, said lastmentioned means comprising a high vacuum condenser.

5. In a heat exchange apparatus, a main condenser, a heater condenser,air exhaust" ing means for the heater condenser delivering to the maincondenser, a flash chamber, means for delivering water from the heatercondenser to the flash chamber, and means for obtaining in said flashchamber a flash temperature gradient at least equal to'5' F.

6. In a heat exchange apparatus, a main condenser, a heater'condenser,air exhausting means for the heater condenser delivering to the maincondenser, a flash chamber,means for delivering water from the heatercondenser to the flash chamber, and means for obtaining in said flashchamber a flash temperature gradient at least equal to 5 F., said meanscomprising a high vacuum condenser.

7. In a heat exchange apparatus, a main condenser, a heater condenser,air exhausting means for the heater condenser deliver-,

ing to the main condenser, a flash chamber, means for delivering waterfrom the heater condenser to the flash chamber, and means for obtainingin said flash chamber a flash temperature gradient at least equal to 5F., said means comprising a high vacuum condenser in combination with amulti-stage air ejecting means.

8. In a heat exchange apparatus, a main condenser and a heatercondenser, means for supplying both steam and water to said condensersin parallel, and means for maintaining a lower pressure in the heatercondenser than inthe main condenser.

9. In a heat exchange apparatus, a main condenser and a heatercondenser,means for supplying both steam and water to said condensers in parallel,and means for-maintaining a lower. pressure in the heater conmy hand. pL I RAYMOND N.

